In our daily lives, we observe that the ice melts under the action of heat, turning into water.
The water boils under more intense heat, turning into water vapor. Water, in this case, has three states: solid, liquid and gas.
They are also called physical states or state of aggregation of matter. When a transformation occurs from one state to another, we call it a physical state change. Each transformation is given a name.
Fusion - change from solid state to liquid.
Vaporization - change from liquid to gaseous state.
Liquefaction or condensation - change from gaseous to liquid state.
Solidification - change from liquid to solid state.
Sublimation - change from solid to gaseous state and vice versa.
The merger obeys some laws:
- a given substance always fuses at the same temperature at a given pressure. This temperature is the melting point (PF). Water melts at 0 ° C and iron at 1500 ° C.
- during melting, the temperature remains constant, ie unchanged.
- during fusion, substances increase in volume except water, iron and silver.
The temperature at which a substance begins to solidify is the same as it begins to melt. The solidification point is the same as the melting point.
The change from liquid to gas phase is given in three ways. Evaporation is a slower process that occurs without a determined temperature and pressure. Boiling is a fast process and depends on each substance that has its temperature and pressure already determined. It is characterized by the appearance of large amount of bubbles.
Boiling obeys some laws:
- substances always boil at the same temperature.
- during boiling, the temperature remains unchanged.
We use the term liquefaction to indicate pressure increase by turning the solid into gas.
Sublimation is a process triggered from a certain temperature and pressure and does not pass through the liquid phase.
Graph of changes in physical states